Polyolefin graft poly(meth)acrylate copolymer-based adhesion promoter for coating polyolefin surfaces

ABSTRACT

The invention relates to a novel halogen-free and acid-free, readily soluble adhesion promoter for polyolefins, said promoter containing (meth)acrylate-grafted, amorphous polyolefins.

FIELD OF THE INVENTION

Polyolefins, such as polyethylene, polypropylene, EPDM, orpoly-α-olefins, are very important as material for example in thepackaging industry, or the automobile industry, or for producingmoldings, for example the case of a cell phone. The only disadvantage ofthese materials, which are easy to process and inexpensive, are theirsurface properties. Polyolefins cannot be directly coated oradhesive-bonded. A primer or some other type of pretreatment of thematerial is required for this purpose. The present invention relates toa novel halogen-free and acid-free adhesion promoter which is intendedfor polyolefin surfaces and which comprises amorphous polyolefinsgrafted with (meth)acrylates. In comparison with a primer, an adhesionpromoter has the advantage that, after formulation, only one processstep is necessary for coating the polyolefin surface.

PRIOR ART

Surface modification of very nonpolar materials, such as polyolefins,has for a long time been a central topic of research in universities andindustry. Polypropylenes or polyethylenes cannot be coated directly withthe polar binders that form the basis for most adhesives or coatings.The adhesion of polymers such as polyesters, polyamides, polyacrylates,polymethacrylates, or polyurethanes to polyolefins is generallyinsufficient for this purpose. Polyolefin foils are therefore mostlysubjected to a high-energy corona treatment for surface-polarizationpurposes prior to the coating process. However, this type of processcannot be used on moldings with edges and with irregularly shapedsurfaces. The only possibility here is flame treatment, which iscomplicated to carry out and often leads to poor results in the edgeregion of particularly irregularly shaped objects. Better results cantherefore be achieved with a polymer solution which has good applicationproperties and which is used as primer.

Primers of this type are often based on halogen-containing paraffins orpolymers. In this connection by way of example, see DE 100 11 384, whichdescribes polydichlorobutadienes. However, the adhesion provided bysystems of this type is not sufficiently good to permit completeomission of pretreatment, for example flame treatment.

WO 2006 124 232 describes a coating system which has to be UV-curedafter application. This type of coating system not only requires anadditional operation but also exhibits further disadvantages, forexample reduced shelflife.

WO 2008 031 677 combines polyolefins with resins as ketone resins and/oron aldehyde resins, as adhesion promoter. However, in comparison withsingle-component systems said system has the disadvantage of possibleoccurrence of phase separation, and of restricted scope of application.

WO 2008 039 595 describes an aqueous coating system which is composed ofpolyolefin-polyether block copolymers having a high proportion ofanionic groups. The person skilled in the art can readily discern thatthis type of system can be used only with very low solids contents, andthat good film formation from an aqueous solution with a high proportionof sparingly soluble polyolefin blocks is difficult.

US 2004 0072 960 describes primers which are obtained through theesterification of carboxylated polyolefins with polyfunctional alcohols.The alcohols involve low-molecular-weight compounds having three or moreOH groups. The person skilled in the art can readily discern that anexcessive degree of carboxylation leads to reduced adhesion topolyolefins, and that on the other hand an inadequate degree ofcarboxylation leads in turn to inadequate polar functionalization of thesurface.

There is a versatile process that has been known for a long time forgrafting of mostly amorphous polyolefins with acrylates and/ormethacrylates. A process in the form of a free-radical solutionpolymerization process has been described by way of example in DE 101 50898. In Badel et al. (J. of Pol. Sc.; Part A: Pol. Chem.; 45, 22, p.5215, 2007) there is a reaction via a reactive extrusion process. Avariant of said process with alternative initiation is found in WO 2004113 399. A controlled graft reaction by way of halogen modification of apolyolefin followed by an atom transfer radical polymerization processis found in Kaneko et al. (Macromol. Symp., 290, pp. 9-14, 2007). Noneof said specifications describes any coating of, or priming of,polyolefin surfaces.

In U.S. Pat. No. 6,310,134, amorphous polyolefins are grafted with acidsor anhydrides, e.g. acrylic acid or methacrylic acid. A disadvantage ofpolymers of this type is poor solubility in organic and aqueoussolvents. Said specification solves the problem of poor solubility byusing very low solids contents below 15% by weight. For uniform coatingit is therefore necessary to use very large amounts of solvent,otherwise the resultant surface is very irregular. In U.S. Pat. No.5,523,358, polypropylenes are analogously grafted with acids. Here, thegraft copolymer is solid during and after the reaction, and the onlypossible method of applying it to the substrate is a heterogeneousmethod or a method that uses extrusion coating. However, both processeslead to primers that are nonuniform and/or very thick.

In U.S. Pat. No. 6,262,182, the problem of the poor solubility of theacid-modified, amorphous polyolefins is solved by usinghigh-boiling-point aromatics as solvents. However, solvents of this typehave great disadvantages during application, in relation to emissionsand toxicity, and also drying temperatures and/or drying times.

Silane reagents can also be used to modify polyolefins, mostly amorphouspoly-α-olefins. Systems of this type are described by way of example inWO 2007 008 765 and EP 1 900 773. A disadvantage of copolymers of thistype is the high proportion of olefin and the proportion of functional,polar groups, which is only small. Said polar groups usually involvealkoxysilyl groups, and these contribute only very little to solubilityimprovement. Again, therefore, these polymers have only poor solubilityand therefore are difficult to apply and cannot be applied withaccuracy.

In EP 1 900 773, poly-α-olefins grafted with a small amount of silylgroups are described. Although said products exhibit very good adhesion,these polymers again have a very high proportion of olefin and have onlypoor solubility in organic solvents, i.e. can be dissolved only at verylow concentrations therein.

In EP 1 601 470 and EP 1 508 579, polyolefins functionalized with silylgroups are likewise described as primers. A disadvantage of systems ofthis type is moreover that the adhesion to the coating is providedexclusively by way of the silyl groups. However, shelflife is known tobe relatively low here, and the proportion of the functional groupstherefore has to be kept low.

In DE 195 16 457, the mixture of modified polyolefins of this type withacid-modified polyolefins is described, as adhesive. The person skilledin the art can readily discern that a system of this type has only verypoor storage properties. In comparison with a polar polymer, an adhesiveof this type also exhibits reduced adhesion values and/or initialadhesion values, because of the small number of functional groups.

In WO 2007/001694, adhesive compositions are described which comprisefunctionalized polymers (e.g. silane-grafted or maleic-anhydride-graftedpropylene polymers) as adhesion promoters. The main polymers areproduced with metallocene catalysts and do not have the requiredproperties, including processing properties.

In WO 2007/002177, adhesive compositions based on random poly(propylene)copolymers having a proportion of at least 50% by weight of propyleneand functionalized polyolefin copolymers and nonfunctionalized adhesiveresins are described, where the enthalpy of fusion of thepoly(propylene) copolymers is from 0.5 to 70 J/g and the proportion ofisotactic propylene triads therein is at least 75%, and the content offunctional monomer units in the functionalized syndiotactic polymersused is at least 0.1%. The poly(propylene) copolymers described arepreferably produced through metallocene catalysis. The functionalizedpolyolefin copolymers encompass functionalized poly(propylene)copolymers, syndiotactic polypropylene copolymers, and the materialsknown as isotactic-atactic polypropylene graft polymers. There is nodescription of main polymers with high proportions of higher 1-olefins,e.g. a proportion of 1-butene. The resultant ratio ofgrafting/functionalization to chain cleavage is poor, because theproportion of isotactic polypropylene units (with a high level offree-radical polymer degradation) is sometimes very high. Functionalmonomer units mentioned are in particular maleic anhydride and glycidylmethacrylates, but also various other functional groups, e.g.vinylsilanes. The polyolefins are modified exclusively with smallamounts of said functional units, and are not grafted with(meth)acrylate mixtures.

OBJECT

It was an object of the present invention to discover a novel processfor coating polyolefin surfaces with coating formulations or,respectively, adhesive formulations which exhibit no direct adhesion onpolyolefins. In particular, the intention is to provide a novel adhesionpromoter which has better usage properties when compared with the priorart.

Another object was to permit coating of the polyolefin surfaces with acoating formulation or, respectively, adhesive formulation which inparticular comprises polar binders.

A third object was to coat the polyolefin surface in such a way that thecoating is continuous and even. This is intended to apply not only tofoils but also to moldings.

A further particular object was that the coating system for polyolefinsurfaces be composed of only one layer, which has maximum ease ofapplication.

A further object was to provide a solution which does not adverselyaffect the weathering resistance of the coating system and whichexcludes any possibility of toxicological concerns.

Other objects not explicitly mentioned are apparent from the entirety ofthe following description, claims, and examples.

ACHIEVEMENT OF OBJECT

The objects are achieved through development of an adhesion promoterwhich is suitable for formulating in coating systems for various typesof substrates, characterized in that

a polymer type A, an olefin polymer or olefin copolymer, is present,a polymer type B, a (meth)acrylate homo- or/and copolymer comprisingstandard methacrylates and/or standard acrylates, is present, anda polymer type AB, a graft copolymer made of polymer type A and polymertype B, is present andthat the amount of polymer type A is from 5% by weight to 60% by weight,that the amount of polymer type B is from 5% by weight to 70% by weight,that the amount of polymer type AB is from 5% by weight to 70% byweight,based on the total mass of polymer types A, B, and AB,and that the ratio by mass of the entirety of polymer types A, B, and ABto the mass of the solvent or of the solvent mixture is from 3:1 to 1:3,preferably from 2:1 to 1:2, and the adhesion promoter is produced aspolymer solution and is further processed as solution.

As an alternative, the adhesion promoter of the invention can also beproduced by means of bulk polymerization or in the form of solutionpolymer which is then dried. In both cases, formulation or furtherprocessing as melt is also possible in 100% systems which are used ascoating formulations.

In this context, coating formulations are film-forming formulationswhich are used as corrosion-protection coating or other coating, or asprimer. The expression coating formulation here can also mean adhesivesor sealants.

The binders of said coating formulations or adhesive formulations can byway of example be based on polyacrylates, on polymethacrylates, onpolyurethanes, on polyesters, on polyamides, on polystyrenes, or on amixture of or copolymer of said components.

Surprisingly, it has been found that this type of polymer as adhesionpromoter in a coating formulation brings about good adhesion onpolyolefins, although the adhesion promoter does not comprise halogensor free acid groups. Halogenated binders have great disadvantages inrelation to weathering resistance, or in respect of toxicology.

Acid-functional polymers have particularly high solution viscosities ormelt viscosities, especially after solution or, respectively, dispersionin organic solvents. These properties make application more difficult orpermit application only from solutions with extremely low solidscontent. The term acid-free here describes a binder which comprises atmost 70 mmol of acid groups/1 g of polymer. The term halogen-freedescribes a binder which comprises at most 10 mmol of halogen atoms/1 kgof polymer.

The polymer type B can optionally comprise additional functional groupswhich do not involve halogens or acid groups, but particularly silylgroups. Surprisingly, it has been found that functionalization withsilyl groups can improve adhesion on polyolefins, such as polypropylene.

It has been found that this adhesion promoter, suitable forcoformulating in coating systems, improves the adhesion of the coatingsystems on various types of substrates, particularly on polyolefinsubstrates, very particularly on polypropylene substrates, and, asadhesion promoter in various types of coating systems which cannototherwise be applied on olefinic surfaces, permits use of said coatingsystems by way of example for polyolefin substrates.

The polyolefins to be coated can by way of example involvepoly-1-butene, polypropylenes, polyethylenes, polyethylene-propylenecopolymers, poly-α-olefins, EPDM, EPM, polybutadienes (including inparticular SEBS block copolymers (styrene-ethylene/butene-styrene blockcopolymers)), or hydrogenated polybutadienes or polyisoprenes.

Surprisingly, it has also been found that the coating system of theinvention has good solubility in aromatic-free solvents at relativelylow temperatures, such as room temperature, or in the form of 100%system has markedly lower melt viscosities when compared with the priorart. Because of these properties, usage properties are markedly improvedin comparison with the prior art.

Polymer Type A

The olefin polymers and olefin copolymers to be used in the invention,corresponding to A, are known per se. These primarily involve polymerscomposed of ethylene, of propylene, of butylene, or/and of otherα-olefins having from 5 to 20 carbon atoms.

Substantially amorphous poly-α-olefins are particularly useful. Examplesof substantially amorphous α-olefins that can be used are homopolymers,e.g. amorphous polypropylene (APP) or amorphous poly-1-butene, orpreferably co- and/or terpolymers having the following monomerconstitution:

-   -   from 0 to 95% by weight, preferably from 3 to 95% by weight, of        one or more α-olefins having from 4 to 20 carbon atoms,    -   from 5 to 100% by weight, preferably from 5 to 97% by weight, of        propene, and    -   from 0 to 50% by weight, preferably from 0 to 20% by weight, of        ethene.

The α-olefin used having from 4 to 20 carbon atoms preferably comprises1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene,3-methyl-1-butene, a methylpentene, such as 4-methyl-1-pentene, amethylhexene, or a methylheptene, alone or in a mixture.

The production of polymers of this type is described by way of examplein EP 0 023 249. The semicrystalline polyolefins of the invention areobtainable by way of example through polymerization of α-olefin monomerswith a TiCl₃.(AlCl₃)_(n) mixed catalyst (n=0.2 to 0.5), where atrialkylaluminum compound is used as cocatalyst, an example beingtriethylaluminum, preferably triisopropylaluminum, particularlypreferably triisobutylaluminum. The activity of the catalyst used isusually from 5000 to 20 000 g of polymer/g of catalyst. The monomerethene is used in gaseous form, whereas the monomers propene and1-butene can be used either in gaseous form or else in liquid form.Higher homologs are used in liquid form. If propene and/or 1-buteneis/are used in liquid form, the pressure maintained in the reactor usedmust be appropriate for the reaction conditions and ensure an adequateconcentration of monomer in the liquid phase. Hydrogen in gaseous formis used as chain-transfer agent. The polymerization process is carriedout in an inert solvent selected by way of example from the group of thealiphatic hydrocarbons. A polymerization process in the initial chargeof monomer is equally possible. The polymerization process is carriedout either in a stirred tank or in a stirred-tank cascade; in oneparticular embodiment, it is also possible to use a tubular reactor ortubular reactor with forced conveying (e.g. a screw-based machine). Thereaction temperature is from 30 to 220° C., preferably from 70 to 150°C., and particularly preferably from 80 to 130° C. Catalyst andcocatalyst are decomposed in suitable manner at the end of the reaction,and the decomposed catalyst constituents here either remain within thepolymer or are removed by way of a washing step. The polymers of theinvention can be stabilized chemically in accordance with the prior art,either in the form of their reaction solution or at a subsequentjuncture, in order to protect them from the damaging effect of increasedtemperatures, insolation, humidity, and oxygen. Examples of stabilizersthat can be used here comprise hindered amines (HALS stabilizers),hindered phenols, phosphites, UV absorbers, e.g. hydroxybenzophenones,hydroxyphenyl-benzotriazoles, etc., and/or aromatic amines. Theeffective amount of stabilizers here is in the range from 0.1 to 2% byweight, based on the polymer. In order to ensure that the granulateand/or powder is flowable, the flow aids usually used in the polymersector can be used. These can be of either inorganic or organic type,and can comprise either low- or high-molecular-weight components, and inall cases it is possible to use not only crystalline but also amorphousflow aids. The flow aids can be either compatible or incompatible, inthe sense of thermodynamic miscibility, with the polyolefins of theclaims. Examples are polyolefin waxes, where these can be based not onlyon polyethylene but also on polypropylene, and Fischer-Tropsch waxes,and also polyolefin waxes based on 1-butene.

The enthalpy of fusion of these unmodified, substantially amorphouspoly-α-olefins is in the range from 0 to 80 J/g, preferably in the rangefrom 1 to 70 J/g, particularly preferably in the range from 1 to 60 J/g.

The enthalpy of fusion is a measure of the crystallinity of the polymer.The poly-α-olefins have relatively low crystallinity, i.e. aresubstantially, but not entirely, amorphous. A certain crystallinity ispresent, and this is essential for the properties demanded. Thecrystalline regions detectable during the melting process extend over awide temperature range from 0° C. to 175° C. and have differentintensity depending on their position. A notable feature of thecrystallinity of the poly-α-olefins is the occurrence of not onlymonomodal but also bi- and multimodal melting signals, some of which areseparate and distinct, and some of which overlap.

The low crystallinity can firstly give high transparency, and secondlycan give flexible mechanical performance. On the other hand, however,higher crystallinity can achieve a particular combination ofadvantageous properties. Fractions A in the binder of the invention withrelatively high crystallinities, e.g. polybutene or butene copolymershaving high butene contents, exhibit by way of example very good tensilestrength. At the same time, they exhibit relatively low surface tack.

The enthalpy of fusion of the crystalline fraction is determined bydifferential calorimetry (DSC) to DIN 53 765 from the second heatingcurve with a heating rate of 10 K/min.

The softening point (determined to DIN EN 1427) of the unmodified,substantially amorphous poly-α-olefins, determined by the ring-and-ballmethod, is moreover from 75 to 165° C., preferably from 79 to 162° C.,particularly preferably from 80 to 158° C., and with particularpreference from 82 to 155° C., and their needle penetration determinedto DIN EN 1426 is at most 55*0.1 mm, preferably from 3 to 50*0.1 mm,particularly preferably from 5 to 45*0.1 mm, and with particularpreference from 7 to 42*0.1 mm. The complex melt viscosity at 190° C.determined by oscillation rheology (determined to ASTM D4440-01:“Standard Test Method for Plastics: Dynamic Mechanical Properties MeltRheology” using an MCR 501 rheometer from Anton Paar with plate-on-plategeometry and with plate diameter of 50 mm, using maximum deformation of1% and a measurement frequency of 1 Hz) is at most 550 000 mPa*s,preferably at most 350 000 mPa*s, particularly preferably from 2500 to250 000 mPa*s, and with particular preference from 5000 to 200 000mPa*s.

In one particular, preferred embodiment, semicrystalline 1-olefinterpolymers based on the monomers ethylene, propylene, and 1-butene areused, where the ethylene content of these determined by ¹³C NMRspectroscopy is from 1 to 12% by weight, preferably from 2 to 10% byweight, particularly preferably from 3 to 9% by weight, and withparticular preference from 3.5 to 8% by weight, while the propylenecontent likewise determined by ¹³C NMR spectroscopy is from 50 to 80% byweight, preferably from 55 to 75% by weight, particularly preferablyfrom 57 to 73% by weight, and with particular preference from 59 to 71%by weight, while the 1-butene content, likewise determined by ¹³C NMRspectroscopy, is from 20 to 50% by weight, preferably from 22 to 45% byweight, particularly preferably from 25 to 40% by weight, and withparticular preference from 27 to 38% by weight, where the proportions ofethylene, propylene, and 1-butene comonomers give a total of 100%. Theneedle penetration (determined to DIN EN 1426) of the preferredterpolymers is from 5 to 28*0.1 mm, preferably from 7 to 26*0.1 mm,particularly preferably from 9 to 25*0.1 mm, and with particularpreference from 10 to 23*0.1 mm, while the softening point (determinedto DIN EN 1427) determined by the ring-and-ball method is from 90 to125° C., preferably from 95 to 122° C., particularly preferably from 97to 120° C., and with particular preference from 99 to 118° C., and thecomplex melt viscosity at 190° C. determined by oscillation rheology(determined to ASTM D4440-01: “Standard Test Method for Plastics:Dynamic Mechanical Properties Melt Rheology” using an MCR 501 rheometerfrom Anton Paar with plate-on-plate geometry and with plate diameter of50 mm, using maximum deformation of 1% and a measurement frequency of 1Hz) is at most 90 000 mPa*s, preferably from 5000 to 75 000 mPa*s,particularly preferably from 7500 to 70 000 mPa*s, and with particularpreference from 10 000 to 65 000 mPa*s. The polyolefin terpolymer usedfor the graft reaction therefore has an ideal property profile, not onlyin respect of its usefulness in the graft process but also for itssubsequent use in the form of grafted product. In particular, theterpolymer preferably used has a good balance between cohesion,adhesion, and flexibility.

The amounts of polymer type A used in the mixture of the invention,based on the polymeric constituents at the end of the reaction, are from10% by weight to 65% by weight, preferably from 20% by weight to 60% byweight, and very particularly preferably from 25% by weight to 55% byweight.

Polymer Type B

The expression (meth)acrylate used hereinafter means the esters of(meth)acrylic acid and here means either methacrylate, e.g. methylmethacrylate, ethyl methacrylate, etc., or acrylate, e.g. methylacrylate, ethyl acrylate, etc., and also mixtures of the two.

Monomers which are polymerized to produce the polymer type B are thoseselected from the group of (meth)acrylates, e.g. alkyl (meth)acrylatesof straight-chain, branched, or cycloaliphatic alcohols having from 1 to40 carbon atoms, for example methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate,tert-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate,cyclohexyl (meth)acrylate, isobornyl (meth)acrylate; aryl(meth)acrylates, e.g. benzyl (meth)acrylate or phenyl (meth)acrylate,where each of these may be unsubstituted or may have aryl moietieshaving from 1 to 4 substituents; other aromatically substituted(meth)acrylates, e.g. naphthyl (meth)acrylate; mono(meth)acrylates ofethers, of polyethylene glycols, of polypropylene glycols, or a mixtureof these having from 5 to 80 carbon atoms, e.g. tetrahydrofurfurylmethacrylate, methoxy(m)ethoxyethyl methacrylate, 1-butoxypropylmethacrylate, cyclohexyloxymethyl methacrylate, benzyloxymethylmethacrylate, furfuryl methacrylate, 2-butoxyethyl methacrylate,2-ethoxyethyl methacrylate, allyloxymethyl methacrylate, 1-ethoxybutylmethacrylate, 1-ethoxyethyl methacrylate, ethoxymethyl methacrylate,poly(ethylene glycol) methyl ether (meth)acrylate, and poly(propyleneglycol) methyl ether (meth)acrylate.

The expression standard methacrylates and, respectively, standardacrylates means esters of (meth)acrylic acid where these are usedindustrially in the synthesis of poly(meth)acrylate moldingcompositions, of adhesives, of sealants, or of binders in coatings. Thisrelates in particular to methyl (meth)acrylate, ethyl (meth)acrylate,propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate,tert-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

The compositions to be polymerized can also comprise, alongside the(meth)acrylates described above, other unsaturated monomers which arecopolymerizable with the abovementioned (meth)acrylates. Among these areinter alia 1-alkenes, such as 1-hexene and 1-heptene, branched alkenes,such as vinylcyclohexane, 3,3-dimethyl-1-propene,3-methyl-1-diisobutylene, and 4-methyl-1-pentene, acrylonitrile, vinylesters, e.g. vinyl acetate, styrene, substituted styrenes having analkyl substituent on the vinyl group, e.g. α-methylstyrene andα-ethylstyrene, substituted styrenes having one or more alkylsubstituents on the ring, e.g. vinyltoluene and p-methylstyrene;heterocyclic compounds, such as 2-vinylpyridine, 3-vinylpyridine,2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine,2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, 9-vinylcarbazole,3-vinylcarbazole, 4-vinylcarbazole, 2-methyl-1-vinylimidazol,vinyloxolane, vinylfuran, vinylthiophene, vinylthiolane, vinylthiazoles,vinyloxazoles, and isoprenyl ethers; maleic acid derivatives, such asmaleimide and methylmaleimide, and dienes, such as divinylbenzene.

The amounts of polymer type B used in the mixture of the invention,based on the polymeric constituents at the end of the reaction, are from35% by weight to 90% by weight, preferably from 40% by weight to 80% byweight, and very particularly preferably from 45% by weight to 75% byweight.

The side branches of the graft copolymers can optionally also comprisesilyl groups in order to improve adhesion.

Examples that may be listed of the silyl moieties are —Si(OMe)₃,—SiMe(OMe)₂, —SiMe₂(OMe), —Si(OPh)₃, —SiMe(OPh)₂, —SiMe₂(OPh),—Si(OEt)₃, —SiMe(OEt)₂, —SiMe₂(OEt), —Si(OPr)₃, —SiMe(OPr)₂,—SiMe₂(OPr), —SiEt(OMe)₂, —SiEtMe(OMe), —SiEt₂(OMe), —SiPh(OMe)₂,—SiPhMe(OMe), —SiPh₂(OMe), —SiMe(OC(O)Me)₂, —SiMe₂(OC(O)Me),—SiMe(O—N═CMe₂)₂ and —SiMe₂(O—N═CMe₂). The meanings of the abbreviationshere are as follows: Me means methyl, Ph means phenyl, Et means ethyl,and Pr means iso- or n-propyl.

One way of incorporating silyl groups of this type in polymer type B iscopolymerization of silyl-functional (meth)acrylates. Examples that maybe listed of the (meth)acrylate moieties are H₂C═CHC(O)O—CH₂—,H₂C═CCH₃C(O)O—CH₂—, H₂C═CHC(O)O—(CH₂)₂—, H₂C═CCH₃C(O)O—(CH₂)₂—,H₂C═CHC(O)O—(CH₂)₃—, and H₂C═CCH₃C(O)O—(CH₂)₃—.

An example of a commercially available monomer would be Dynasylan® MEMOfrom Evonik Degussa GmbH. This comprises3-methacryloyloxypropyltrimethoxysilane.

Another way of incorporating silyl groups of this type in polymer type Bis copolymerization of other silyl-functional monomers which have acopolymerizable olefinic group, e.g. an allyl or vinyl group.

An example of a commercially available monomer would be Dynasylan® VTMOfrom Evonik Degussa GmbH. This comprises vinyltrimethoxysilane.

A third way of incorporating silyl groups in polymer type B is the useof silyl-functional chain-transfer agents which by way of example have athiol group.

An example of a commercially available monomer would be Dynasylan® MTMOfrom Evonik Degussa GmbH. This comprises3-mercaptopropyltrimethoxysilane. Other available silanes are3-mercaptopropyltriethoxysilane, 3-mercaptopropyl-methyldimethoxysilane,and mercaptomethylmethyldiethoxysilane (from ABCR). The proportion ofsilyl-functional monomers in the monomer mixture B is from 0% by weightto 20% by weight, preferably from 0% by weight to 10% by weight, andparticularly preferably from 0% by weight to 5% by weight.

The Polymer Type AB Production of the Graft Polymers AB

The graft polymer AB is generally produced by producing a solution ofstrength from 5 to 50% by weight, preferably from 10 to 25% by weight,of the polymer of type A, preferably of a poly-α-olefin, in a suitablesolvent which is inert under polymerization conditions and which has anormal boiling point above the process temperature, by stirring thepolymer in the solvent, preferably above the softening point of thepoly-α-olefin. To this solution, which should be as homogeneous aspossible, a suitable initiator is then added at reaction temperature,preferably a peroxidic free-radical initiator. After an initiation timeof from 0 to 60 min, preferably from 0 to 30 min, particularlypreferably from 1 to 20 min, the monomer mixture for synthesis of thepolymer type B is added, or is metered into the mixture over arelatively long period. It is preferable to use peresters, such astert-butyl peroctoate. The initiator concentration depends on the numberof graft sites desired and on the desired molecular weight of thesegment B. Initiator concentration is generally from 0.2% by weight to3% by weight, based on the polymer. This process naturally forms apoly(meth)acrylate of type B in parallel with the graft reaction.

As an alternative for poly-α-olefins which are not miscible with thesolvent under the conditions described, for example because of asoftening point which is above the boiling point of the solvent, it ispossible to add emulsifiers. In this case, the graft reaction is carriedout analogously in an organic dispersion.

The polymerization time is usually from 4 to 8 hours. The polymerizationtemperature is not critical. However, it is generally in the range from−20° C. to 200° C., preferably from 0° C. to 130° C., and particularlypreferably from 50° C. to 120° C.

In an alternative method, using a suitable emulsifier, a dispersion isproduced from component A, and monomers which lead to component B aregrafted onto this dispersion under the reaction conditions suitable forthis purpose, by analogy with the first method. The structure ofemulsifier can be similar to that of the AB system. The processes forproducing suitable emulsifiers of type AB are known per se. By way ofexample, the procedure can use the transfer grafting method (cf. alsoHouben-Weyl, Methoden der Org. Chemie [Methods of organic chemistry],volume 1411, p. 114, H. A. J. Battaerd, G. W. Tregear, Polymer Reviews,Vol. 16, Interscience (1967)).

The process can be carried out in suitable solvents, such as H₂O;acetates, preferably butyl acetate, ethyl acetate, propyl acetate;ketones, preferably ethyl methyl ketone, acetone; ethers; aliphatics,preferably pentane, hexane; biodiesel; or else plasticizers, such aslow-molecular-weight polypropylene glycols or phthalates. It ispreferable to produce the binder of the invention in aromatic-freesolvent systems. Aromatics are toxicologically hazardous and, even inindustrial applications, should be avoided as far as possible.Surprisingly, it has been found that the production of graft copolymersin the invention can be carried out particularly successfully inacetates, such as butyl acetate.

The softening point of the poly-α-olefin often restricts the choice ofthe solvent. The boiling point of the selected solvent should ideally beabove that range. As an alternative, the graft reaction can be carriedout under pressure.

It is also possible to use mixtures made of the solvents described abovefor the carrier system. The ratio by mass of the entirety of the polymertypes A, B, and AB to the mass of the solvent or of the solvent mixturecan be from 3:1 to 1:3, preferably from 2:1 to 1:2. The solvent mixturepreferably comprises no aromatics.

The binders of the invention can be produced not only by solutionpolymerization but also by means of emulsion, miniemulsion,microemulsion, suspension, or bulk polymerization.

One particularly preferred method is bulk polymerization, in particularcontinuous bulk polymerization. This can take the form of reactiveextrusion or can be carried out in a polymerization kneader. This typeof process has the advantage that the product is obtained in a form freefrom solvents and can be used in this form directly in meltapplications, for example hot-melt adhesives or reactive hot-meltadhesives. A solvent-free system is also particularly suitable for whatare known as high solids coatings, the principle of which ismaximization of solids content. Formulation with an undiluted product ofthe invention avoids further dilution of this type of coatingformulation. In contrast, in the case of polymers produced by means ofsolution polymerization, an additional process step is first required toremove the solvent, prior to any of said applications. In the case ofemulsion polymers or suspension polymers, the residual water first hasto be removed by drying. This is particularly important in the case ofreactive, possibly moisture-crosslinking systems.

In the case of a graft process in solution, the reaction temperature forthe graft process is from 30 to 200° C., preferably from 40 to 190° C.,particularly preferably from 50 to 180° C., and with particularpreference from 55 to 140° C. The solution grafting process takes placeeither batchwise or continuously. In the case of batchwise conduct ofthe reaction, the solid polymer (e.g. in the form of granules, powder,etc.) is first dissolved in the solvent used. As an alternative to this,a suitably prepared polymerization solution from themain-polymer-production process is used directly and brought to reactiontemperature. The monomer(s) and the free-radical initiator(s) are thenadded. In one particularly preferred embodiment, solvent, mainpolymer(s), and monomer(s) are used as initial charge and brought toreaction temperature, while the free-radical initiator(s) is/are meteredinto the mixture continuously over a defined period. This has theadvantage that steady-state free-radical concentration is low, and theratio of graft reaction to chain cleavage is therefore particularlyadvantageous (i.e. more graft reaction and less chain cleavage). Inanother particularly preferred embodiment, solvent and main polymer(s)are used as initial charge and brought to reaction temperature, whilemonomer(s) and free-radical initiator are continuously metered into themixture over a defined period—together (e.g. in the form of a mixture)or separately from one another. This has the advantage that bothsteady-state free-radical concentration and monomer concentration at thereaction site are low, and this suppresses not only chain cleavage butalso formation of homopolymers. This is particularly important whenmonomers are used which have a marked tendency toward thermallyinitiated (homo)polymerization at reaction temperature. It is veryparticularly preferable that, following the various defined meteringperiods, a further amount of free-radical initiator(s) is metered intothe mixture, in order to minimize the content of residual monomers inthe reaction solution. It is preferable to use a stirred tank asreactor, but it is equally possible to use alternative reaction vessels,e.g. batch kneading reactors, and this is particularly preferred in thecase of low reaction temperatures and/or high polymer concentrations.

In the case of continuous conduct of the reaction, the solid polymer isfirst dissolved in at least one solvent, in one or more feed vessels(e.g. stirred tanks), and is then fed continuously into the reactionvessel(s). In an alternative, likewise particularly preferred,embodiment, an appropriately prepared polymer solution is used directlyfrom a main-polymer-production process. In another, likewiseparticularly preferred, embodiment, the solid polymer (e.g. in the formof powder, granules, pellets, etc.) is fed together with at least onesolvent continuously into a (single- or multiscrew) screw-based machineor a Conti kneader, dissolved with exposure to heat and/or shear, and isthen fed continuously into the reaction vessel(s). Reaction vessels orreactors that can be used for carrying out the continuous graft reactionin solution are continuous stirred tanks, stirred-tank cascades, tubularreactors, tubular reactors with forced conveying (e.g. screw-basedmachines), reactive kneaders, and also any desired combinations ofthese. If tubular reactors with forced conveying are used, thesepreferably involve extruders, and it is possible here to use eithersingle-, twin-, or multiscrew extruders. It is particularly preferableto use twin- and/or multiscrew extruders. A particularly preferredreactor combination for the continuous production of the modifiedpolymers of the invention in solution is a reactor combination made oftubular reactor, tubular reactor with forced conveying, and continuousstirred tank in any desired sequence, and it is preferable here that theremoval of residual monomers and of volatile byproducts/degradationproducts also takes place either in the tubular reactor with forcedconveying or in the continuous stirred tank.

As an alternative, a melt process is preferably involved, where at leastone free-radical initiator is fed directly into the melt. In particular,in this process variant, the temperature of the polymer composition atthe time of metering of at least one free-radical initiator into themixture is above the SADT (self-accelerating decompositiontemperature=temperature above which self-accelerating decomposition canbegin to occur) of at least one of the free-radical initiators meteredinto the mixture.

The reaction temperature for the graft process in the melt is from 160to 250° C., preferably from 165 to 240° C., particularly preferably from168 to 235° C., and with particular preference from 170 to 230° C.

The grafting in the melt takes place either batchwise or continuously.In the case of batchwise conduct of the reaction, the solid polymer(e.g. in the form of granules, powder, pellets, etc.) is first meltedand optionally homogenized. As an alternative, an appropriately preparedpolymer melt is used directly from a polymerization process and broughtto reaction temperature. Monomer(s) and free-radical initiator(s) arethen added.

In one particular embodiment, monomer(s) and polymer melt are mixedhomogeneously and brought to reaction temperature, while thefree-radical initiator(s) is/are metered into the mixture continuouslyover a defined period. This has the advantage that steady-statefree-radical concentration is low, and the ratio of graft reaction tochain cleavage is therefore particularly advantageous (i.e. more graftreaction and less chain cleavage).

In another particularly preferred embodiment, the polymer melt is usedas initial charge and homogenized, while monomer(s) and free-radicalinitiator are metered into the mixture continuously together (e.g. inthe form of a mixture) or separately over a defined period. This has theadvantage that not only steady-state free-radical concentration but alsomonomer concentration at the reaction site remains low, and thissuppresses not only chain cleavage but also formation of homopolymer.The latter is particularly important when using monomers which have atendency toward thermal (homo)polymerization at the prevailing reactiontemperature. The reactor used preferably comprises a stirred tank withstirrer assembly operating close to the wall, or a reactive kneader.

In the case of continuous conduct of the reaction, the solid polymer isfirst melted in one or more feed vessels (e.g. stirred tanks), and isthen fed continuously into the reaction vessel(s). In an alternative,likewise particularly preferred, embodiment, an appropriately preparedpolymer melt is used directly from a polymerization process. In anotherlikewise particularly preferred embodiment, the solid polymer (e.g. inthe form of powder, granules, pellets, etc.) is fed continuously into a(single- or multiscrew) screw-based machine or a Conti kneader, meltedwith use of heat and/or shear, and then fed continuously into thereaction vessel(s). Reaction vessels or reactors that can be used forcarrying out the continuous graft reaction in the melt are continuousstirred tanks, stirred-tank cascades, tubular reactors, tubular reactorswith forced conveying (e.g. screw-based machines), reactive kneaders,and also any desired combinations of these. If tubular reactors withforced conveying are used, these preferably involve extruders, and it ispossible here to use either single-, twin-, or multiscrew extruders. Itis particularly preferable to use twin- and/or multiscrew extruders. Aparticularly preferred reactor combination for the continuous productionof the modified polymers of the invention in the melt is a reactorcombination made of tubular reactor, tubular reactor with forcedconveying, and continuous stirred tank in any desired sequence, and itis preferable here that the removal of residual monomers and of volatilebyproducts/degradation products also takes place either in the tubularreactor with forced conveying or in the continuous stirred tank.

Chain-transfer agents can also optionally be used for adjusting to thedesired molecular weight for the segments B. Examples of suitablechain-transfer agents are sulfur chain-transfer agents, in particularchain-transfer agents containing mercapto groups, e.g. dodecylmercaptan. The concentration of chain-transfer agents is generally from0.1% by weight to 2.0% by weight, based on the entire polymer.

Another method for producing the graft polymers AB is provided by thehydroperoxidation of a poly-α-olefin as first step. The hydroperoxidegroups thus formed along the chain can initiate the graft polymerizationof the vinyl monomers in a subsequent stage (cf. H. A. J. Battaerd, G.W. Tregear, Polymer Reviews, ibid.).

The amounts of polymer type AB used in the mixture of the invention arebased on the polymeric constituents at the end of the reaction, from 5%by weight to 70% by weight, preferably from 20% by weight to 60% byweight, and very particularly preferably from 25% by weight to 50% byweight.

The binders of the invention can be added as adhesion promoters toformulations with various application sectors. The adhesion promoter ofthe invention is preferably added to formulations for coating polyolefinsurfaces, particularly for coating polypropylene surfaces. By way ofexample, the material here can involve a coating, an adhesive, or asealant. Another possibility is a primer which, after application, canin turn be coated with a second formulation or substance.

The surfaces to be coated can also involve materials other thanexclusively polyolefins. The adhesion promoters of the invention havethe great advantage that, in adhesive formulations or coatingformulations, they certainly also improve adhesion with respect tometals, such as aluminum, steel, or zinc, with respect to plastics otherthan polyolefins, e.g. PVC, PET, polystyrene, ABS, polycarbonate,polymethacrylate, e.g. Plexiglas from Evonik, polyamide, such asnylon-6, or polyethers, such as polyoxymethylene, and with respect toother materials, such as wood, granite, concrete, or glass.

In the invention, the adhesion promoter is admixed with a coatingformulation or an adhesive formulation. Said formulations can involvesolvent-based or aqueous systems, or else 100% systems, e.g. in the formof melts, such as hot-melts or reactive hot-melts. Said coatingformulations are composed of one or more binders and optionallypigments, auxiliaries, process materials, and/or fillers, alongside theadhesion promoter and optional solvents.

The pigments can involve organic or inorganic—commercially available ornovel—pigments added in the form of pure substance or in predispersedform.

The binders involve the conventional binders used in adhesiveformulations, in sealant formulations, and in coating formulations.Examples that may be mentioned, without in any way thereby restrictingthe invention, are polyacrylates, polymethacrylates, polycarbonates,polyolefins, such as EPDM, EPM, PE, PP, and poly-α-olefins, orcopolymers made of various olefins; polyamides, polyesters, polyethers,polystyrenes, or two-component or other polyurethanes.

The auxiliaries or process materials can involve the additives usuallyused in adhesive formulations, in sealant formulations, and in coatingformulations. Examples that may be mentioned, without in any way therebyrestricting the invention, are defoaming agents, emulsifiers,compatibilizers, stabilizers, dispersing agents, antioxidants,scratch-resistant additives, processing agents for reducing abrasionduring further processing, catalysts, crosslinking agents, accelerators,or other adhesion promoters.

The adhesive formulation of the invention can comprise furtherconstituents which are necessary in order to achieve specificproperties, e.g. deformability, adhesive power, processability,crosslinking rate, crosslinking density, (melt or solution) viscosity,strength, crystallization rate, tack, shelflife, etc. In one particularembodiment of the present invention, the proportion of the otherconstituents is particularly preferably at most 10% by weight. This hasthe advantage that the properties of the adhesive formulation are inessence those of the adhesion promoter of the invention that is used.This type of adhesive formulation can be produced at very low cost.

As an alternative, in another embodiment of the present invention, theproportion of the other constituents can be >10% by weight. In thiscase, the other constituents make up at most 95% by weight of the entireformulation, preferably at most 90% by weight, particularly preferablyat most 85% by weight, with particular preference at most 80% by weight.

The other constituents can involve crosslinking accelerators, inparticular silanol condensation catalysts, inorganic and/or organicfillers, which can optionally be electrically conductive or insulating,inorganic and/or organic pigments, which can optionally be electricallyconductive or insulating, synthetic and/or natural resins, in particularadhesive resins, synthetic and/or natural oils, inorganic and/ororganic, synthetic and/or natural polymers, which can optionally beelectrically conductive or insulating, inorganic and/or organic,synthetic and/or natural fibers, which can optionally be electricallyconductive or insulating, inorganic and/or organic stabilizers, and/orinorganic and/or organic flame retardants.

The other constituents in particular comprise resins, where the resinsare used in order to achieve appropriate adaptation of particularproperties of the adhesive layer, in particular the tack and/oradhesion, the flow behavior and creep behavior of the adhesive layer,and/or the viscosity of the adhesive, for particular requirements.Natural resins and/or synthetic resins can be involved here. In the caseof natural resins, said natural resins comprise, as main constituent,abietic acid (e.g. rosin). The resins can moreover involve terpeneresins or polyterpene resins, petroleum resins, and/or coumarone-indeneresins, and the materials here particularly involve what are known asC₅-resins and/or Cg-resins, and/or involve copolymers made ofC₅-/C₉-resins. The proportion of the resins in the hot-melt adhesiveformulation of the invention is in particular at most 45% by weight,preferably from 1 to 40 by weight, particularly preferably from 2 to 30%by weight, and with particular preference from 3 to 20% by weight, basedon the entire formulation.

The hot-melt adhesive formulations of the invention can moreovercomprise traditional amorphous (or semicrystalline) poly(α-olefins)(known as APAOs) as further constituents. The abovementioned amorphous(or semicrystalline) poly(α-olefins) can involve homo-/co- and/orterpolymers made of ethylene, propylene, 1-butene, or of linear and/orbranched 1-olefins having from 5 to 20 carbon atoms, where these areobtainable by way of example through traditional Ziegler-Natta catalysisor metallocene catalysis. The proportion of the amorphouspoly(α-olefins) is in particular at most 50% by weight, preferably atmost 40% by weight, and particularly preferably at most 30% by weight,based on the entire formulation. It is preferable that the furtherconstituents involve crystalline or semicrystalline polyolefins, wherethese in particular comprise isotactic polypropylene, syndiotacticpolypropylene, polyethylene (HDPE, LDPE, and/or LLDPE), isotacticpoly(1-butene), syndiotactic poly(1-butene), copolymers of these, and/orcopolymers of these with linear and/or branched 1-olefins having from 5to 10 carbon atoms. It is further preferable that the crystalline orsemicrystalline polyolefins involve chemically modified polyolefins,where the chemical modification in particular comprises modificationusing maleic anhydride, itaconic anhydride, acrylic acid, acrylates,methacrylates, unsaturated epoxy compounds, silane acrylates, silanes,and hydroxyalkylsilanes.

The other constituents can moreover comprise polymers having polargroups. Polymers having polar groups comprise polystyrene copolymers(e.g. with maleic anhydride, acrylonitrile, etc.), polyacrylates,polymethacrylates, (co)polyesters, polyurethanes, (co)polyamides,polyether ketones, polyacrylic acid, polycarbonates, and also chemicallymodified polyolefins (e.g. poly(propylene-graft-maleic anhydride) orpoly(propylene-graft-alkoxyvinylsilane)). The mixing of the polymers ofthe invention with the polymers comprising polar groups here can lead toimmediate and/or delayed reactive linkage of the polymer chains, whichpreferably leads to improved compatibility between the two polymerphases, this being by way of example discernible from a shift of theglass transition temperatures of the polymers used. It is particularlypreferable that as a consequence of the reactive linkage the polymerphases exhibit a shared glass transition temperature, i.e. exhibitmacroscopic miscibility.

The other constituents can moreover comprise homo- and/or copolymers (orelse oligomers) based on ethylene, propylene, butadiene, styrene, and/oracrylonitrile, where these can comprise, as other comonomers, a dieneand/or a cyclic diene, butadiene, styrene, and/or isoprene, and inparticular these polymers are block copolymers, in particular beingrubbers, e.g. natural or synthetic rubber, poly(butadiene),poly(isoprene), styrene-butadiene rubber, styrene-isoprene rubber, andnitrile rubber. The proportion of the polymers based on butadiene,styrene, and/or isoprene is at most 20% by weight, preferably from 1 to15% by weight, particularly preferably from 1.5 to 10% by weight, and inparticular from 2 to 9% by weight, based on the hot-melt adhesiveformulations. In the case of oligomers, it is preferable that butadieneoligomers are involved.

The other constituents can moreover comprise elastomeric polymers basedon ethylene, on propylene, on a diene, and/orcis,cis-1,5-cyclooctadiene, exo-dicyclopentadiene,endo-dicyclopentadiene, 1,4-hexadiene, and 5-ethylidene-2-norbornene,and in particular the materials here involve ethylene-propylene rubber,EPM (double-bond-free, ethylene content from 40 to 75% by weight),and/or EPDM. The proportion of the polymers based on ethylene, onpropylene, on a diene, and/or cis,cis-1,5-cyclooctadiene,exo-dicyclopentadiene, endo-dicyclopentadiene, 1,4-hexadiene, and5-ethylidene-2-norbornene is usually at most 20% by weight, preferablyfrom 1 to 15% by weight, particularly preferably from 1.5 to 10% byweight, and in particular from 2 to 9% by weight, based on the hot-meltadhesive formulations.

As an alternative, the other constituents can comprise waxes, inparticular modified and unmodified waxes, where these preferably involvecrystalline, semicrystalline, and/or amorphous polyolefin waxes based onpolyethylene, polypropylene, and/or poly(1-butene), paraffin waxes,metallocene waxes, microwaxes, polyamide waxes, polytetrafluoroethylenewaxes, and/or Fischer-Tropsch waxes. The proportion of the waxes is atmost 50% by weight, preferably from 1 to 40% by weight, particularlypreferably from 2 to 30% by weight, and with particular preference from3 to 20% by weight, based on the hot-melt adhesive formulations.

The other constituents can moreover comprise fillers, where the fillersare used in order to achieve controlled adaptation of specific propertyprofiles of the adhesive layer, e.g. the temperature use range,strength, shrinkage, electrical conductivity, magnetism, and/or thermalconductivity, for specific requirements. The fillers generally involveinorganic and/or organic fillers. The inorganic fillers are particularlythose selected from silicas (inclusive of hydrophobized silicas),powdered quartz, chalks, titanium dioxide, zinc oxide, zirconium oxide(the latter three preferably in nanoscale form), barite, glass particles(in particular spherical particles for increasing light reflection),glass fibers, carbon fibers, asbestos particles, asbestos fibers, and/ormetal powders. Examples of organic fillers are carbon black, bitumen,crosslinked polyethylene, crosslinked rubber mixtures, synthetic fibers,e.g. polyethylene fibers, polypropylene fibers, polyester fibers,polyamide fibers, aramid fibers, Saran fibers, MP fibers, or naturalfibers, such as straw, wood, wool, cotton, silk, flax, hemp, jute,and/or sisal. The proportion of the fillers is at most 80% by weight,preferably from 1 to 60% by weight, particularly preferably from 5 to40% by weight, and with particular preference from 7 to 30% by weight,based on the hot-melt adhesive formulations.

The other constituents can equally comprise crosslinking accelerators.This is preferable particularly when the polymers of the invention areused in an adhesive bond which is intended to achieve its maximumload-bearing capability shortly after the joining process. Suitablecrosslinking accelerators are a wide variety of chemical compounds, inparticular Brønsted and/or Lewis acids, e.g. acetic acid, itaconic acid,zinc(II) acetate, cadmium acetate, zinc oxide, zinc stearate, zinc(II)chloride, tin(IV) chloride, dibutyltin oxide, dibutyltin dilaurate,bismuth citrate, bismuth(III) oxide, bismuth titanate,tetrabutylgermanium, tetrabutyltin, titanium boride, titanium(IV) oxide,titanium acetylacetonate, tributyl titanate, sodium chloride,magnesium(II) chloride, zinc acetylacetonate, zinc methacrylate, zincniobate, tin(II) oxide, tin(IV) oxide, zirconium(IV) acetylacetonate,zirconium(IV) oxide, and/or zirconium(IV) silicate.

The other constituents can moreover comprise stabilizers, where theseare used in order to protect the adhesive formulation from externaleffects, e.g. the effect of (processing) heat, shear stress, insolation,humidity, and oxygen. Examples of suitable stabilizers are hinderedamines (HALS stabilizers), hindered phenols, phosphites, and/or aromaticamines (for example those commercially available with the product namesIRGANOX, KINOX, DOVERNOX, WESTON, IRGAPHOS, DOVERPHOS, and/or IONOL). Itis particularly preferable that the stabilizers used in the inventioncomprise only one hydrolytically active terminal group per molecule. Theproportion of the stabilizers in the abovementioned formulations is atmost 3% by weight, preferably from 0.05 to 2.5% by weight andparticularly preferably from 0.1 to 2% by weight, based on the hot-meltadhesive formulations. In one particular embodiment, reactive linkage ofthe stabilizer(s) to the polymer modified in the invention occurs, withresultant prevention of stabilizer migration out of the adhesive bond.

The other constituents can moreover comprise one or more oils, wherethese can involve natural and/or synthetic oils. The viscosity ofthis/these one or more oil(s) at the processing temperature ispreferably from 0.1 to 1000 mPa*s, preferably from 1 to 750 mPa*s, mostpreferably from 2 to 500 mPa*s. Examples of suitable oils are mineraloils, (medicinal) white oils, isobutene oils, butadiene oils,hydrogenated butadiene oils, and/or paraffin oils. The proportion of theone or more oils is at most 50% by weight, preferably from 1 to 45% byweight, particularly preferably from 3 to 40% by weight, and inparticular from 5 to 38% by weight, based on the hot-melt adhesiveformulations.

The hot-melt adhesive formulations can moreover comprise inorganicand/or organic pigments, UV-active substances, organic and/or inorganicnucleating agents which accelerate the crystallization of the polymersand thus reduce the open time of the adhesive bond.

In an embodiment of the hot-melt adhesive formulations of the inventionto which further preference is given, the formulations described aboveinvolve multiphase blends.

The fillers can involve the fillers conventional in industry, examplesbeing silicates, phyllosilicates, carbon blacks, or silicas, but thisshort list is not intended in any way to restrict the invention.

The coated surfaces can by way of example involve the surfaces of foils,of granules, of injection moldings or of moldings produced in any otherway, of composite materials, or of laminates. All of these products arehereinafter covered by the term “workpiece”.

The workpieces coated in this way can be used in the packaging industry,e.g. for food or drink or for pharmaceutical products, in automobileconstruction, in shipbuilding, in the electronics industry, in theconstruction industry, in furniture construction, in engineering, or inthe production of toys.

The method of coating with the coating formulation or adhesiveformulation can by way of example be analogous to that for coil coating,by way of rolls. It is also possible to apply the primer to the surfaceby a spray process or coating process. Other methods that can also beused are those such as spincoating or dipcoating. It is also equallypossible to remove the solvent prior to the application process, and toprime the substrate surface by means of extrusion coating orcoextrusion. In one preferred embodiment the adhesion promoter isformulated as undiluted polymer or dried solution polymer in a 100%system, e.g. for melt applications.

The formulations can comprise from 0.1% by weight to 40% by weight ofthe adhesion promoters of the invention, preferably from 1% by weight to30% by weight, and particularly preferably from 2% by weight to 20% byweight.

EXAMPLES Measurement of Dynamic Viscosity

Dynamic viscosity is measured to DIN EN ISO 53018.

Measurement of Solids Content

Rapid weighing-out of from 0.3 to 0.5 g of polymer solution to anaccuracy of 0.1 mg into a tared aluminum dish followed by addition of 5mL of acetone as entrainer. The solvent is then evaporated first for 60min at room temperature and then for a further 60 min at 105° C. Thespecimen is cooled in a desiccator and weighed, and the difference inweight is determined. Three measurements are carried out for eachspecimen. In the event of deviations greater than 0.2% by weight,additional measurements are carried out.

Determination of PP Adhesion of Coatings

The PP adhesion of a binder on various substrate surfaces was studied toDIN EN ISO 2409 by means of a crosscut test inclusive of adhesive-tapepeel (hereinafter Tesa peel test). To this end, the unaltered specimenwith the solids content established after the synthesis process isapplied with a wet layer thickness of 60 μm to the substrate by means ofa wire-wound rod, and dried overnight at room temperature. The result isevaluated using grades from 0 (particularly good adhesion) to 5 (noadhesion). The tables state two values: the first involves visualassessment after the Tesa peel test, and the second involves visualassessment after the cutting process.

Determination of Miscibility of the Adhesion Promoters with Coatings

In order to demonstrate the miscibility of the adhesion promoters withcoating formulations, the samples in the examples were mixed withsolvent-based coating formulations in such a way that the adhesionpromoter makes up a proportion of 5% by weight of the solids. Saidmixtures were stirred for 60 min, and miscibility was assessed visuallyafter two hours. Miscibility is assessed here using values from 0(homogeneous mixture with no noticeable inhomogeneity) to 5 (completephase separation).

The coating systems for the mixing experiments comprised a 50% strengthsolution of a polymethacrylate binder DEGALAN LP 64/12 and a PU basecoatcomposed of 47.1% by weight of Synocure 854 BA 80, 12.4% by weight ofVestanat 2500LV, 7.6% by weight of Vestanat T 1890L, 0.16% by weight ofTegokat 218 (1% strength in n-butyl acetate), 0.096% by weight of TegoGlide 100, and 4.32% by weight of Chroma-Chem 844, and also 14.16% byweight of n-butyl acetate, and 14.16% by weight of toluene. The totalsolids content of the formulation prior to the addition of the adhesionpromoter solution is therefore 71.68% by weight.

a) Examples of the Polyolefins (Polymer Type A) Used in the Invention

Ethene, propene, and 1-butene are polymerized in n-butane in alaboratory autoclave at 95° C., using a mixed catalyst of a crystallinetitanium chloride in the form of aluminum-reduced TiCl₃ (TiCl₃*0.33AlCl₃) and triisobutylaluminum (in a ratio by weight of 1:4), withhydrogen used as chain-transfer agent. The monomers ethene and propeneare metered continuously into the mixture during the reaction time of 3h, and the monomer 1-butene is used as initial charge. After 3 h,isopropanol is admixed with the reaction mixture, thus terminating thereaction. An acetone solution of a stabilizer (e.g. Irganox) is thenadded. Unreacted monomers, and also the solvent n-butane, are evaporatedin an evaporator. The melt of the substantially amorphous polyolefin isdischarged at a temperature of about 190° C.

The properties of the polymers are as follows

Polymer constitution η* Experi- (¹³C NMR) T_(soft.) PEN 190° C. ment No.Ethene Propene 1-Butene [° C.] [0.1 mm] [mPa * s] comp1 0 2 98 118 5  6750 1 2 24 74 85 13 24 300 2 0 61 39 132 9   3100 3 3.5 84.5 12 106 1448 600 4 5.1 61.4 35 117 15 223 000  5 4 67.3 28.7 112 10 41 800

Comparative example comp1 is not of the invention, because of the verylow propylene content.

b) Examples of the Graft Copolymers (Polymer Type AB) Synthesized in theInvention Example 6

240 g of n-butyl acetate and 100 g of polyolefin of type 1 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 0.78g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 75 g of methylmethacrylate, 75 g of n-butyl acrylate, and 2.3 g of tert-butyl2-ethyl-perhexanoate into the mixture over a period of 90 min.

After a further 150 min of reaction time, the polymer solution is cooledto 50° C. and diluted with 180 g of n-butyl acetate in order to reducesolution viscosity. After a further 60 min of stirring forhomogenization, the dispersion is cooled to room temperature.

Example 7

316 g of n-butyl acetate and 120 g of polyolefin of type 3 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 1.46g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 140 g of methylmethacrylate, 140 g of n-butyl acrylate, and 4.25 g of tert-butyl2-ethylperhexanoate into the mixture over a period of 90 min.

After a further 150 min of reaction time, the polymer solution is cooledto 50° C. and diluted with 244 g of n-butyl acetate in order to reducesolution viscosity. After a further 60 min of stirring forhomogenization, the dispersion is cooled to room temperature.

Example 8

327 g of n-butyl acetate and 120 g of polyolefin of type 5 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 2.91g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 280 g of n-butylacrylate and 8.51 g of tert-butyl 2-ethylperhexanoate into the mixtureover a period of 90 min.

After a further 150 min of reaction time, the polymer solution is cooledto 90° C. and diluted with 243 g of n-butyl acetate in order to reducesolution viscosity. After a further 60 min of stirring forhomogenization, the dispersion is cooled to room temperature.

Example 9

316 g of n-butyl acetate and 120 g of polyolefin of type 5 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 1.46g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 136 g of methylmethacrylate, 136 g of n-butyl acrylate, and 8 g of3-methacryloyloxypropyltrimethoxysilane, and 4.25 g of tert-butyl2-ethylperhexanoate into the mixture over a period of 90 min.

After a further 150 min of reaction time, the polymer solution is cooledto 50° C. and diluted with 244 g of n-butyl acetate in order to reducesolution viscosity. After a further 60 min of stirring forhomogenization, the dispersion is cooled to room temperature.

Example 10

316 g of n-butyl acetate and 120 g of polyolefin of type 5 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 1.46g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 272 g of n-butylacrylate, 8 g of 3-methacryloyloxypropyltrimethoxysilane, and 4.25 g oftert-butyl 2-ethylperhexanoate into the mixture over a period of 90 min.

After a further 150 min of reaction time, the polymer solution is cooledto 50° C. and diluted with 244 g of n-butyl acetate to reduce solutionviscosity. After a further 60 min of stirring for homogenization, thedispersion is cooled to room temperature.

Example 11

316 g of n-butyl acetate and 120 g of polyolefin of type 5 are used asinitial charge in a jacketed vessel with attached thermostat, refluxcondenser, blade stirrer, and internal thermometer. The polyolefin iscompletely dissolved within one hour at 100° C., with stirring, and 1.46g of tert-butyl 2-ethylperhexanoate are then admixed therewith. Ametering pump is then used to meter a mixture made of 272 g of n-butylmethacrylate, 8 g of 3-methacryloyloxypropyltrimethoxysilane, and 4.25 gof tert-butyl 2-ethylperhexanoate into the mixture over a period of 90min.

After a further 150 min of reaction time, the polymer solution is cooledto 50° C. and diluted with 244 g of n-butyl acetate to reduce solutionviscosity. After a further 60 min of stirring for homogenization, thedispersion is cooled to room temperature.

Results of Example Synthesis Process

Solids Experi- η_(190° C.) content Polyolefin/ ment No. [mPa*s] % by wt.Appearance Poly(meth)acrylate 6 3500 36.2 white, disperse 40/60 7 160040.2 white, disperse 30/70 8 360 40.4 white, disperse 30/70 9 2300 40.6white, disperse 30/70 10 180 40.6 white, disperse 30/70 11 6800 39.8white, disperse 30/70

On the basis of these results it can be shown that the viscosities foundwere surprisingly low. Even with a solids content of about 40% by weightand with a proportion of 30% by weight or 40% by weight of polyolefin inthe solid, the solutions or dispersions, respectively, have goodprocessability, and all of them exhibit no, or only slight, phaseseparation. Only example 8 exhibited slight phase separation after 7days of storage, to give a clear liquid phase and a white disperseliquid phase. However, the specimen could easily be redispersed byshaking or stirring. The polymer dispersions of the invention thereforehave surprisingly good shelflife.

Visual Assessment of the Films after Tesa Peel Test and Crosscut Test

Visual assessment Miscibility Crosscut 5% in methacrylate 5% in PUExample Tesa peel test test system basecoat 6 1 3 1 1 7 1 3 0 0 9 0 2 00

Measurement of direct adhesion on PP foils showed that the adhesionpromoters of the invention are suitable for providing adhesion onnonpolar substrates. These experiments showed that the binders of theinvention can also be used as primers for further coatings.

The mixing experiments with a methacrylate binder and, respectively, aPU basecoat show good compatibility—and therefore coformulatability—withcoating systems. From the combination of these two results, it can beconcluded that the material is very useful as adhesion promoter.

1. An adhesion promoter for comprising a polymer type A, a polyolefin or a polyolefin mixture, a polymer type B, a (meth)acrylate homo- or/and copolymer comprising standard methacrylates and/or standard acrylates, and a polymer type AB, a graft copolymer made of polymer type A and polymer type B, wherein the adhesion promoter is in the form of a melt, a dispersion, or a solution and is halogen-free and acid-free.
 2. The adhesion promoter as claimed in claim 1, wherein polymer type B and polymer type AB have silyl groups.
 3. The adhesion promoter as claimed in claim 1, wherein the adhesion promoter is coformulated as polymer solution, the ratio by mass of the entirety of polymer types A, B, and AB to the mass of the solvent or of the solvent mixture is from 3:1 to 1:3, and the solvent mixture comprises no aromatics.
 4. The adhesion promoter as claimed in claim 1, wherein the adhesion promoter is coformulated as a melt and 100% system.
 5. The adhesion promoter, as claimed in claim 1, wherein polymer type A comprises an atactic polypropylene, atactic poly-1-butene, and/or co- and/or terpolymer of the following monomer constitution: from 0 to 95% by weight of one or more α-olefins having from 4 to 20 carbon atoms, from 5 to 100% by weight of propene, and from 0 to 50% by weight of ethene.
 6. The adhesion promoter as claimed in claim 5, wherein the α-olefins having from 4 to 20 carbon atoms are selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 3-methyl-1-butene, a methylpentene, preferably 4-methyl-1-pentene, a methylhexene, and a methylheptene, alone or in a mixture.
 7. The adhesion promoter, as claimed in claim 1, wherein that the polymer type AB is a graft copolymer having a polyolefin main chain and poly(meth)acrylate side chains.
 8. The adhesion promoter, as claimed in claim 1, wherein monomers which lead to component B are fed into a mixture of a polymer of type A and of an initiator in a solvent, and are polymerized.
 9. An adhesive formulation for the adhesive bonding of polyolefin substrates, wherein the adhesive comprises an adhesion promoter as claimed in claim
 1. 10. A coating formulation comprising an adhesion promoter as claimed in claim
 1. 11. A sealant formulation comprising an adhesion promoter as claimed in claim
 1. 12. A primer comprising an adhesion promoter as claimed in claim
 1. 13. The formulation as claimed in claim 9, wherein the formulation is free from solvents.
 14. The formulation as claimed in claim 9, wherein the formulation comprises water as solvent.
 15. A foil, molding, tube, or cable sheathing, coated with a formulation as claimed in claim
 13. 